With the current emphases that has been placed upon protection of children of tender ages from harm due to their being able to open containers of medicines, acids, soaps, etc., development of so called "child-proof" or, more correctly, "child-resistant" containers and closures, has been very rapid.
Many of these child-resistant combinations have employed threaded caps and containers with threaded necks, the caps and containers being provided with cooperating means which function to prevent the child of tender years from removing the cap from the container after it has been seated thereon.
Devices of this type which are practical also must be so designed as to provide for capping the containers by the use of conventional capping equipment. Since many such products previously have been packaged in vials or, glass or plastic bottles with threaded necks and screw-on caps, or with bayonet or snap-on caps most packaging organizations already possess automatic capping machinery which is capable of placing such caps onto the container necks.
However, the tolerances of manufacturing of both the containers and the caps are such that when screw-type caps are put on by automatic capping machines, they do not all reach the same angular position relative to the containers on which they are set by the capping machines. Similarly even bayonet or snap-on caps are not always forced down onto the containers the same distance when they are applied.
If the caps have internal sealing liners which function to render the necks of the containers leak proof, variations in the degree of tightening of the caps onto the necks of the bottles may be important as a result of cumulations in the tolerances. When cork was inexpensive, because it is highly resilient and does not take a "set" if it is squeezed too tightly, it frequently was utilized as the main body of the sealing liners so that it would compensate easily for these variations and would maintain all of the containers in liquid tight condition even if the caps squeezed the liners to differing degrees. However, when other liner materials are used, the liners will take a "set" and may not be replaced by the user to a distance on the container neck such that the liner will keep the container leakproof.
It is the object of the instant invention, therefore, to provide a cap for a container which has a resilient shoulder which compensates for variations in cumulated tolerances to insure that the liner seals the container neck when the cap reaches its closed position on the container neck, particularly when the closed position is predetermined as in the cases of threaded caps having child-resistant means, bayonet-type threads or beveled snap-on retaining means.
These and other more specific object and advantages of a closure embodying the invention will be better understood from the specification and from the drawings which follow.